Abstract
Previous studies using combined techniques of site-directed mutagenesis and electrophysiology of voltage-gated Na+ channels have demonstrated that there are significant overlaps in the regions that are important for the two fundamental properties of the channels, namely gating and permeation. We have previously shown that a pore-lining residue, W402 in S5-S6 region (P loop) in domain I of the μ1 skeletal muscle Na+ channel, was important in the gating of the channel. Here, we determined the role of an adjacent pore-lining negatively charged residue (E403) in channel gating. Charge neutralization or substitution with positively charged side chain at this position resulted in a marked delay in the rate of recovery from slow inactivation. Indeed, the fast inactivation process appeared intact. Restoration of the negatively charged side chain with a sulfhydryl modifier, MTS-ethylsulfonate, resulted in a reactivation profile from a slow-inactivated state, which was indistinguishable from that of the wild-type channels. We propose an additional functional role for the negatively charged residue. Assuming no major changes in the pore structure induced by the mutations, the negatively charged residue E403 may work in concert with other pore regions during recovery from slow inactivation of the channel. Our data represent the first report indicating the role of negative charge in the slow inactivation of the voltage-gated Na+ channel.
| Original language | English (US) |
|---|---|
| Journal | American Journal of Physiology - Cell Physiology |
| Volume | 284 |
| Issue number | 5 53-5 |
| State | Published - May 1 2003 |
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Keywords
- Site-directed mutagenesis
- Slow inactivation
- Sodium channel
ASJC Scopus subject areas
- Clinical Biochemistry
- Cell Biology
- Physiology
Cite this
A negatively charged residue in the outer mouth of rat sodium channel determines the gating kinetics of the channel. / Zhang, Zhao; Xu, Yanfang; Dong, Pei Hong; Sharma, Dipika; Chiamvimonvat, Nipavan.
In: American Journal of Physiology - Cell Physiology, Vol. 284, No. 5 53-5, 01.05.2003.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - A negatively charged residue in the outer mouth of rat sodium channel determines the gating kinetics of the channel
AU - Zhang, Zhao
AU - Xu, Yanfang
AU - Dong, Pei Hong
AU - Sharma, Dipika
AU - Chiamvimonvat, Nipavan
PY - 2003/5/1
Y1 - 2003/5/1
N2 - Previous studies using combined techniques of site-directed mutagenesis and electrophysiology of voltage-gated Na+ channels have demonstrated that there are significant overlaps in the regions that are important for the two fundamental properties of the channels, namely gating and permeation. We have previously shown that a pore-lining residue, W402 in S5-S6 region (P loop) in domain I of the μ1 skeletal muscle Na+ channel, was important in the gating of the channel. Here, we determined the role of an adjacent pore-lining negatively charged residue (E403) in channel gating. Charge neutralization or substitution with positively charged side chain at this position resulted in a marked delay in the rate of recovery from slow inactivation. Indeed, the fast inactivation process appeared intact. Restoration of the negatively charged side chain with a sulfhydryl modifier, MTS-ethylsulfonate, resulted in a reactivation profile from a slow-inactivated state, which was indistinguishable from that of the wild-type channels. We propose an additional functional role for the negatively charged residue. Assuming no major changes in the pore structure induced by the mutations, the negatively charged residue E403 may work in concert with other pore regions during recovery from slow inactivation of the channel. Our data represent the first report indicating the role of negative charge in the slow inactivation of the voltage-gated Na+ channel.
AB - Previous studies using combined techniques of site-directed mutagenesis and electrophysiology of voltage-gated Na+ channels have demonstrated that there are significant overlaps in the regions that are important for the two fundamental properties of the channels, namely gating and permeation. We have previously shown that a pore-lining residue, W402 in S5-S6 region (P loop) in domain I of the μ1 skeletal muscle Na+ channel, was important in the gating of the channel. Here, we determined the role of an adjacent pore-lining negatively charged residue (E403) in channel gating. Charge neutralization or substitution with positively charged side chain at this position resulted in a marked delay in the rate of recovery from slow inactivation. Indeed, the fast inactivation process appeared intact. Restoration of the negatively charged side chain with a sulfhydryl modifier, MTS-ethylsulfonate, resulted in a reactivation profile from a slow-inactivated state, which was indistinguishable from that of the wild-type channels. We propose an additional functional role for the negatively charged residue. Assuming no major changes in the pore structure induced by the mutations, the negatively charged residue E403 may work in concert with other pore regions during recovery from slow inactivation of the channel. Our data represent the first report indicating the role of negative charge in the slow inactivation of the voltage-gated Na+ channel.
KW - Site-directed mutagenesis
KW - Slow inactivation
KW - Sodium channel
UR - http://www.scopus.com/inward/record.url?scp=0037405154&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0037405154&partnerID=8YFLogxK
M3 - Article
C2 - 12540378
AN - SCOPUS:0037405154
VL - 284
JO - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
JF - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
SN - 1931-857X
IS - 5 53-5
ER -